MESOSCALE MULTI-PHYSICS SIMULATION OF SOLIDIFICATION IN SELECTIVE LASER MELTING PROCESS USING A PHASE FIELD AND THERMAL LATTICE BOLTZMANN MODEL

摘要

Selective laser melting (SLM) is a powder bed based additive manufacturing process by melting fine-grained metallic powders with a laser heating source. Understanding the solidification of alloys during SLM process is of importance for accurate prediction of microstructures and properties for process design and optimization. In this study, a multi-physics model is developed to simulate evolution of alloy microstructure during solidification, which incorporates heat transfer, fluid dynamics, kinetics of phase transformations, and grain growth. In this integrated simulation framework, the phase field method for the dendritic growth of a dilute binary alloy is coupled with the thermal lattice Boltzmann method for the melt flow and heat transfer. The effects of latent heat, melt flow and cooling rate on solidification process are also investigated. The multi-physics simulation results provide new insight to predict the complex solidification process more accurately than single-physics approaches.